Why Distant Things Look Fainter (But Not Dimmer)
▶ DRILLThe light companion to Why Distant Objects Look Smaller. As George carries a lantern away, its glow spreads over a bigger and bigger square — twice as far means four timesthe area — so Liza's eye catches less light in total, and it looks fainter (the inverse-square law). But the lamp also looks smaller, and every bit of its surface stays exactly as bright: it shrank, it didn't dim. That's why the Moon looks small but never washed out. Use the Explain it for a kid / a grown-up switch to set the depth.
The big idea — a light spreads out as it travels, so far away your eye catches less of it in total — that's why distant things look fainter (it falls as 1 over the distance squared). But the surface itself never gets darker — it just looks smaller (the angular-size drill again). That's the answer to the riddle from "Why Distant Objects Look Smaller": faraway things look smaller but not dimmer. The Moon, a far window, a distant wall — small, never washed out.